A window shade system includes a window shade (e.g., roller shade) that is typically wound around a shade tube. The shade tube is typically mounted to a bracket on each end. The bracket usually includes mechanical components and a chain to enable the shade tube to be rotated. The rotation of the shade tube via the chain raises and lowers the roller shade. The brackets are mounted to a wall or other structure. The window shade system may include brackets mounted in a window pocket, overhead, ceiling mounting, jamb mounting, top-down mounting, sloped mounting, horizontal mounting or skylight mounting. The window shade system may also be controlled with a motor, wherein the motor receives instructions from a switch or software.
The typical bracket includes a looped chain that rotates through a sprocket within the bracket. The looped chain may hang down any length. The window shade industry often prefers that the bottom of the looped chain hangs down to near the bottom of the window shade (e.g., 4 inches from the window sill). If the system is configured such that the sprocket is the same diameter as the shade tube, the ratio of turns between the sprocket and the tube is typically 1:1. If each turn of the sprocket lowers the shade 1 foot, then a 10 foot diameter loop of a chain is often used with a 10 foot long window shade. Therefore, a chain length of about 20 feet is needed in order to lower a 10 foot window shade because only about half (i.e., about 10 feet) of the chain rotates through the sprocket. In other words, only the chain length from the sprocket and down to the bottom of the chain loop is used. As shown in FIG. 1, only the chain length from point A to point B (only about half the chain) is used to fully lower and fully raise the window shade.
Such window shade brackets may include a bead stop, wherein the bead stop is bigger than the other chain elements. The bead stop is also bigger than the opening in the bracket, such that the bead stop cannot enter the bracket and cannot rotate around the sprocket. Therefore, the bead stop prevents a user from pulling on the chain beyond the point where the chain fully raises or fully lowers the window shade. The bead stop may be set in place at a specific location along the chain such that the bead stops create upper and lower limits for pulling the chain and rotating the shade tube (and thus, raising or lowering the shade to the appropriate position). Bead stops have been used on window shade systems for decades, so consumers are very familiar with bead stops, and consumers have come to expect a bead stop to control their use of the bracket chain. As such, it is very important for window shade system manufacturers to include the bead stops on the bracket systems to give the consumer the same experience as in the past.
A bracket may also include gears which may reduce the force needed to rotate the chain. A geared bracket also includes a looped chain that rotates through a sprocket within the bracket, but the ratio of turns between the sprocket and the tube may be different than 1:1. For example, in a planetary gear system, when the ratio of turns between the sprocket and the tube is 3:1, the force needed to pull the chain in a geared bracket is ⅓ of a non-geared bracket. However, the chain must be pulled more times to fully open or close the shade. In this example, it takes 3 turns of the sprocket to lower the shade 1 foot, so it takes 30 turns of the sprocket to lower the 10 foot window shade. As such, with a chain length of 20 feet (10 feet on each side of the sprocket), pulling the chain from the sprocket to the bottom of the chain loop will cause the sprocket to rotate 10 turns, but only result in ⅓ of the shade movement. In other words, a point on the chain would need to rotate 1.5 laps to fully lower the 20 foot shade (also known as a continuous chain since the chain needs to keep rotating through the bracket). Therefore, a point on the chain would need to rotate through the sprocket during the 1.5 rotations. As such, a bead stop cannot be used because the bead stop is bigger than the opening in the bracket and cannot enter the bracket to rotate around the sprocket.
A geared bracket may also include a planetary gear type system (or epicyclic gearing). A planetary gear system may include a central gear (sun gear) and one or more outer gears (planet gears) revolving around the central gear. Existing brackets using a planetary system include the sun gear permanently mated to the sprocket, wherein a ring gear is used as the sprocket. As such, when the chain is pulled, the sprocket rotates causing the sun gear to rotate, which in turn rotates the shade tube in a 3:1 ratio (3 turns of the sprocket results in 1 turn of the shade tube). In other words, the input power is to the sun gear, and the output power is to the shade tube hub 280 (carrier).
However, such a planetary system is limited to a ratio that must be larger than 2:1. In particular, to obtain a lower ratio, the sun gear would need to have a larger diameter (and be the same size as the sprocket) to the point where no planet gears would be able to fit around the sun gear. As set forth above, because the ratio must be larger than 2:1, the chain must rotate through the sprocket more than one lap. As such, a planetary gear type system, a bead stop cannot be used on the chain because, as mentioned above, the bead stop is bigger than the opening in the bracket and cannot enter the bracket to rotate around the sprocket.
Importantly, without a bead stop, after the shade is fully lowered, the consumer could continue to unravel the shade off of the shade tube. Moreover, without a bead stop, after the shade is fully raised, the consumer could continue to rotate the shade such that the hembar (on the bottom of the shade) gets pulled into the roller system. If the hembar is pulled into the roller, the shade can flip over the shade tube, the shade or tube may disengage, the shade may get damaged, the hembar may get damaged or the hembar may not be able to be easily un-wound or easily exit from the roller system. Systems have been created to minimize these problems caused by not having a bead stop such as, for example, a device to restrict the number of rotations of the shade tube, or a hook that catches and stops the hembar before it enters the roller system. However, such systems include extra components and extra moving parts, which add weight, cost and failure points. As such, a need exists for a bracket that includes a geared system, but still operates with a chain having bead stops.